frisk vs lark about

frisk is a noun but lark about is not a noun.

Word	Noun	Adjective	Verb	Adverb
frisk	Yes	No	Yes	No
lark about	No	No	Yes	No

As verbs, frisk and lark about are synonyms defined as:

Other synonyms of frisk include cavort, disport, frolic, gambol, lark, rollick, romp, run around, skylark, sport.

frisk (noun)	lark about (noun)
the act of searching someone for concealed weapons or illegal drugs

frisk (verb)	lark about (verb)
search as for concealed weapons by running the hands rapidly over the clothing and through the pockets	play boisterously
play boisterously